UseDatabaseNullSemantics仍会生成NULL检查 [英] UseDatabaseNullSemantics still generating NULL checks

问题描述

我的上下文对象(构造函数)上有这个

I have this on my context object (constructor):

this.Configuration.UseDatabaseNullSemantics = true;

但是即使设置了这个，该查询:

But even with this set, this query:

var query = (from i in _repo.Invoices
             join o in _repo.Orders on i.orderid equals o.orderid
             join o2 in _repo.Orders on o.linkedorderid equals o2.linkedorderid  into leftOrders
             from lo in leftOrders.DefaultIfEmpty()
             where invoiceIds.Contains(i.invoiceid)
             select new
             {
                i, lo
             }).ToList();

返回此SQL:

SELECT 
    [Extent1].[invoiceid] AS [invoiceid], 
    [Extent1].[custid] AS [custid], 
    [Extent1].[orderid] AS [orderid], 
    [Extent1].[orderamount] AS [orderamount], 
    [Extent1].[invoiceamount] AS [invoiceamount], 
    [Extent1].[paidamount] AS [paidamount], 
    [Extent1].[paidstatus] AS [paidstatus], 
    [Extent1].[printdate] AS [printdate], 
    [Extent1].[updateddate] AS [updateddate]
    FROM   [dbo].[invoices] AS [Extent1]
    INNER JOIN [dbo].[orders] AS [Extent2] ON [Extent1].[orderid] = [Extent2].[orderid]
    LEFT JOIN [dbo].[orders] AS [Extent3] ON ([Extent2].[linkedorderid] = [Extent3].[linkedorderid]) OR (([Extent2].[linkedorderid] IS NULL) AND ([Extent3].[linkedorderid] IS NULL))
    WHERE [Extent1].[invoiceid] IN (3098489, 3123185, 3156838)

不难发现我遇到了System.OutOfException错误，因为我有成千上万的具有linkedorderid等于NULL的订单.

It's not hard to see that I'm getting a System.OutOfException error since I have tons of orders with linkedorderid equals NULL.

如果我删除了OR (([Extent2].[linkedorderid] IS NULL) AND ([Extent3].[linkedorderid] IS NULL))，查询运行正常，并返回所有具有子工作订单的发票...

If I remove OR (([Extent2].[linkedorderid] IS NULL) AND ([Extent3].[linkedorderid] IS NULL)) query runs fine and returns all invoices that have or not children work orders...

任何想法我该如何解决?

Any idea how can I solve this ?

推荐答案

这项工作有效吗?如果删除(或(null并且为null))子句时发布的查询正确，那么我认为这将执行相同的查询. (这假定联接中没有逻辑错误，如其他帖子中所建议的那样.)

Does this work? If the posted query is correct when you remove the (or (is null and is null)) clause, then I think this will execute the same query. (This assumes there isn't a logic error in the joins, as suggested in other posts.)

var query = (from i in _repo.Invoices
    from o in _repo.Orders.Where(c => c.orderid == i.orderid)
    from o2 in _repo.Orders.Where(c => c.linkedorderid == o.linkedorderid).DefaultIfEmpty()                          
    where invoiceIds.Contains(i.invoiceid)
    select new
    {
       i, o2
    }).ToList();

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